Conventionally, an engine includes electric components such as fuel injection nozzles, an alternator, and many types of sensors. These electric components are connected through wire harnesses each of which binds power supply lines for transmitting electric power or signal lines for transmitting signals in a form suitable for a wiring route. In such an engine, power supply lines for fuel injection nozzles and the like, power supply lines for sensors and the like, signal lines for sensors and the like are sorted according to functions, and each of the sorted groups of lines is configured as a wire harness. See Patent Document 1, for example.
The engine according to Patent Document 1 is wired with wire harnesses that are sorted into wire harnesses including only power supply lines which are apt to generate noise (electromagnetic wave) and wire harnesses including only signal lines which are susceptible to the noise. The wire harnesses including only power supply lines and the wire harnesses including only signal lines are further bound together and mounted on the engine. However, the wire harnesses are bound together in arbitrary forms and fixed to the engine, and thus variations occur in the binding ways and the mounting positions on the engine. Accordingly, the wire harnesses may be bound in a state in which influence of the noise cannot be sufficiently suppressed or in a state in which the wire harnesses easily contact the neighboring components.